I don’t know if the fediverse is robust enough to fight them off as the pot of gold they see begins to overflow. It’s hard balance to find.

By now I think it's not a balance which can be found. I think "migration to the next thing" is just part of the nature of online identity, if it's important to you.

After some time the weaknesses of certain systems and platforms will start to show, especially if they start becoming "mainstream". And then chances are good that pressure will mount, as a new platform will bring up which aims to adress at least some of the weaknesses of the previous platform. Rinse. Repeat.